OptionalConfigAbsolute path of the mj.config file the value came from, if one was found.
OptionalConfiguredThe additionalSchemaInfo value from mj.config, if any.
OptionalEnvValue of RSU_ADDITIONAL_SCHEMA_INFO_PATH, if set.
Directory relative paths fall back to when there is no config file (env override, or no config file found).
Inputs to ResolveAdditionalSchemaInfoPathFrom. Kept separate from module state so the resolution rule can be tested and reused without a loaded config.